The embodiments described herein relate generally to motors, and more particularly, to methods and systems used to control the operating characteristics of an electrically commutated motor.
Electrically commutated motors (ECMs) are used in a variety of systems operating in a variety of industries. ECMs are used to power products such as fans used in heating, ventilation and air conditioning systems (HVAC). ECMs are subject to many operating conditions and often, the operating conditions necessitate that operating characteristics of the ECM change to match the requirements of the associated application (i.e., different speeds or airflow requirements for HVAC applications). More specifically, control circuits for ECMs must typically be changed to enable the ECM to operate with different operating characteristics for different applications and/or for different voltage levels.
In some known systems, the speed-torque characteristics of motors are an integral part of the design and rating of the system. When the motor within such a system is upgraded to include a brushless direct current (DC) motor or an existing ECM is repaired/retrofitted, the characteristics that depend on the speed-torque curve of the upgraded/repaired motors have to be re-evaluated. The re-evaluation is necessary since the new ECM could have a different speed-torque curve than the previous ECM and consequently, if provided with the same speed-torque curve as the previous ECM, operate at several hundred RPMs faster than the new ECM's capabilities. This operational characteristic of an ECM can result in the ECM having higher speeds under some conditions than it did prior to upgrade or retrofit/repair.
Further, in some known systems, supply or input voltages are limited to the field technician who is upgrading or repairing components such as the ECM or associated circuits. In such cases, it is desirable to have available ECM replacement motor and controls operable at either 240V or 460V. Motor operation over such a two to one range of input voltages could require a regulating device for full load operation over the voltage range. Known voltage regulating systems include a boost regulator to increase voltage or include a buck regulator to drop voltage. These regulating systems include considerable active electronics with passive components, which components increase the cost and complexity of the system while reducing system reliability.